We now have experimental gates which will eventually be daily jobs to
build, test and publish images to dockerhub. First step is to mimic our
tarball publisher to build images -> save them to temp space -> run set
of jobs that will sign off these images -> move images to regular
tarballs.
Depends-on: I0231bd07415ef05b3f4f937e32a9df4cd0643672
Change-Id: If578edcd4e431c0b93cb9cedcc3d9db47d41a637